What is automatic transmission fluid?
Automatic transmission fluid (ATF) is the fluid used in vehicles with automatic transmissions. It is usually red or green.
Why check the automatic transmission fluid level?
Automatic transmission fluid is the lifeblood of the transmission. The fluid produces the hydraulic pressure needed to operate the transmission. It also cools and lubricates the transmission. When the fluid level is low, the pump may draw air into the system. The air in the hydraulic system interrupts the proper flow of automatic transmission fluid. Damage can occur very quickly when the transmission fluid is low.
How to check the automatic transmission fluid level?
For transmissions with a dipstick, the procedure is the same as described above.
Many Fords, Toyotas, GMs and other vehicles no longer have an automatic transmission dipstick for checking the fluid level. Automakers are eliminating automatic transmission dipsticks. Newer transmissions are far more complex than older models and the transmission fluid levels are far more critical. Special procedures are required to check the automatic transmission fluid level in these models.
If you want to go further, learn how to change automatic transmission fluid:
- Drain the transmission fluid: First, disconnect the cooling line running from the transmission to the radiator. Connect a piece of rubber tubing to the pipe and place the free end of the tube in an empty container. Start the engine and let it idle. Transmission fluid should flow out of the cooling line and into the container. As soon as the fluid stops flowing, turn off the engine. You can then reconnect the cooling line to the radiator.
- Remove the bolts holding the drain oil pan to the bottom of the transmission.
- Clean the drain pan with transmission fluid.
- Replace the filter.
- Replace the gasket.
- Replace the pan: Once the filter and gasket are in place, put the pan back on the transmission. Hand-tighten the bolts for the first few turns so that you don’t strip the threads. Then use a torque wrench to finish tightening the bolts. Do not overtighten the bolts or you will damage the threads in the transmission and dent the pan.
- Fill with automatic transmission fluid: Dexron III ATF is the most common, but refer to the owner’s manual to choose the appropriate automatic transmission fluid. Check the amount as well.
If your vehicle hesitates when your automatic transmission shifts gears, check the transmission fluid level before you let any mechanic, start talking about servicing or adjusting your transmission or selling you a new one. To check your automatic transmission fluid, look for a dipstick handle sticking out of your transmission. This is located toward the rear of an in-line engine on vehicles with rear-wheel drive as shown here:
Where to find the transmission fluid dipstick in an inline engine?
If your vehicle has front-wheel drive, the transmission fluid dipstick is sticking out of the transaxle, as shown here.
Where to find the transmission fluid dipstick if you have a front-wheel-drive?
The fluid level in a manual transmission must be checked with the vehicle on a hoist to enable the technician to reach a plug in the bottom of the transmission
To check your automatic transmission fluid, follow these steps:
- Pull out the dipstick. With the gearshift in Neutral or Park and the parking brake on, let your engine run. Be sure the engine is warm when you pull out the dipstick. (Don’t turn off the engine.)
- Check the fluid. Dip the tip of your index finger into the fluid on the dipstick and rub the fluid between your finger and the tip of your thumb. The transmission fluid on the dipstick should be pinkish and almost clear. If it looks or smells burnt or has particles in it, have a mechanic drain and change the fluid.
- Wipe the dipstick with a clean, lint-free rag; then reinsert it and pull it out again. If the transmission fluid is clear but doesn’t reach the “Full” line on the dipstick, use a funnel to pour just enough transmission fluid down the dipstick tube to reach the line. Don’t overfill!
There are several types of transmission fluid. Each is made for a specific type of automatic transmission. Newer transmissions from the major automakers require different fluid than older ones. Because so many different kinds of transmissions are around these days, check your owner’s manual or dealership to find out which type of fluid your vehicle requires.
A faulty transmission and one that’s just low on fluid share many of the same symptoms! If your vehicle hesitates when your automatic transmission shifts gears, check the transmission fluid level before you let any mechanic start talking about servicing or adjusting your transmission or selling you a new one. Adding transmission fluid is a lot cheaper than replacing the whole transmission system!
SYMPTOMS FOR LOW TRANSMISSION FLUID
Your vehicle shouldn’t lose automatic transmission fluid in normal operation, so if the level is down, there’s a good chance there’s a leak somewhere. Consult a service professional immediately to have it addressed to avoid possible damage to the transmission. Also, some automatic transmissions do not have dipsticks or may require that a service professional inspect the automatic transmission fluid level. Check the vehicle’s owner or service manual.
STEP-BY-STEP INSTRUCTIONS FOR CHECKING YOUR VEHICLE’S TRANSMISSION FLUID
- Park vehicle on a level surface, engage the parking brake, and start the engine. Leave the car in neutral or park. Let the engine warm-up and continue to run throughout operation unless the vehicle’s owner’s manual says otherwise. (Be aware that some [automatic transmission fluid levels are checked with the engine off. (Check owner’s manual.)
- Locate automatic transmission fluid dipstick, typically near where the transmission or transaxle meets the rear of the engine. It looks similar to the oil dipstick.
- Remove automatic transmission fluid dipstick. Wipe clean, reinsert fully and remove again. CAUTION: FLUID MAY BE HOT!
- Observe markings at end of the dipstick. Your dipstick might have two markings for “full”—one warm, one cold. If the automatic transmission fluid level does not come up to the “warm” line, you’ll need to add automatic transmission fluid.
- Insert a long funnel into an automatic transmission fluid dipstick hole. Carefully add automatic transmission fluid in small increments and recheck levels each time until the fluid level reaches the “warm” line. CAUTION: DO NOT OVERFILL OR SPILL AUTOMATIC TRANSMISSION FLUID ON HOT ENGINE PARTS!
- Reinsert automatic transmission fluid dipstick fully. You’re done!
Frequently Asked Questions:
1. Do you check your transmission fluid when it’s hot or cold?
Pull the dipstick out again and check the fluid level. If the engine is cool, it should be at the upper end of the “ COLD " mark. If the engine is hot, the level should be at the upper end of the “ HOT ” mark. If it’s lower, you should add some amount of automatic transmission fluid
2. Do you check transmission fluid with the car on or off?
Park vehicle on a level surface, engage the parking brake, and start the engine. Leave the car in neutral or park. Let engine warm-up and continue to run throughout operation unless the vehicle’s owner’s manual says otherwise. (Be aware that some automatic transmission fluid levels are checked with the engine off.
3. What happens if you overfill the transmission fluid?
If you add too much transmission fluid, you will notice that it may foam, and that can bring about erratic gear shifting. … When an automatic transmission is overfilled, the fluid foams, leading to gear shifting problems, oil starvation as well as transmission damage.
4. Do manual cars have transmission fluid?
Yes, even a manual needs transmission fluid. The type of fluid can vary from car to car, however. Some manuals require conventional engine oil, and others function best with automatic transmission fluid. So make sure you’re putting in the fluid that’s specified for your car.